The parallel hybrid drive trains of vehicles of the known art usually have a starting element, designed as a friction-locking clutch between an internal combustion motor and the output of the vehicle, in order to start the vehicle by means of the internal combustion engine in a known way, whereby the starting element is initially actuated by slipping during the starting process. If a vehicle, such as a hybrid vehicle, is constructed with a drive unit configured as an electric motor, the controlled and regulated slip operation of the starting element is not required, if the starting process of the vehicle is realized exclusively via the electric motor, as electric motors, unlike conventional internal combustions engines, have no minimum rotational speed.
A method of controlling and regulating a drive train of a hybrid vehicle and a drive train of a hybrid vehicle with a friction-locking starting element is known from DE 10 2004 002 061 A1. At the same time, with the method of the invention for controlling and regulating a drive train of a hybrid vehicle with an internal combustion engine, an electric motor, a shifting element located between the electric motor and a drive in a force flow of the drive train, and a continuously variable transmission capacity and a clutching device located between the electric motor and the internal combustion engine, by means of which the electric motor and the internal combustion engine can be functionally connected, a drive train of a hybrid vehicle can be driven such that it is possible to transition from actuation of the hybrid vehicle by the electric motor to parallel actuation of the hybrid vehicle via the electric motor and the internal combustion engine, or to exclusive actuation of the hybrid vehicle by the internal combustion engine of the hybrid vehicle, as well as a starting operation of the internal combustion engine via the electric motor, without reactive torque from the drive train being perceptible to the driver.
In addition, during operation of the drive train, the transmission capacity of the shifting element during a starting operation of the internal combustion engine is set in such a way, that a torque independent of a starting operation of the internal combustion engine is applied to the output of the drive train, whereby torque changes to the output, which occur due to the starting of the internal combustion engine, are preferably avoided by slip operation of the shifting element.
With this method, the rotational speed of the electric motor is raised during the starting phase of the internal combustion engine to a rotational speed value at which it is guaranteed that the shifting element between the electric motor and the output of the drive train is kept in a slip operation during the entire starting operation of the internal combustion engine. The rotational speed value is calculated by means of an algorithm that is implemented in the motor control, the transmission control and/or in a superordinate torque manager.
In addition, there are drive trains of motor vehicles known from prior art with internal combustion engines having minimum operating speeds that are constructed to realize a starting operation of the vehicle on the part of internal combustions engine with a starting element configured as a hydrodynamic torque converter.